I recommend a royal tea party theme . A tea party works in any space and can have any size crowd, preferably a smaller one. For a tea party, you could very well host in your own home, at your own dining room table, in your living room or sun room, or backyard (backyard tea parties are best if you have a patio or deck).

First if they don't mind setup the backyard for movies and watch Disney movies and maybe put up a sheet and have stuff to get dressed up like Disney people and take pictures

It's my 16th but there will probably be around 15 - 20 people at my house I want it to be like a kids party but with a teenage element involved what can I do ? It's I'm July thanks